Bathroom design residential installations typically use 1½ inch pipes for drains. You'd be surprised how much hair and hair you shed from that channel. The bigger the drain, the less likely it is to clog up. The cost of upgrading to a 2-inch drain is very low, and unless your framing allows it, you should consider increasing the drain in your shower to 2 inches.
Also, if you live in an area where the temperature drops below freezing in winter, it's important that your water supply lines are not routed through the outer wall.
To illuminate the ceiling, consider the recessed lamps on the ceiling. Add one (or two) to your shower with a suitable shower head. Install a dimmer switch so you can adjust the air in your bathroom. You'll want to think about how to use the mirror in your bathroom and whether you want aesthetic or functional lighting. Whether you're applying make-up or shaving, neatly placed bright light fixtures go a long way to helping you see up close what you're doing.
Large tiles are harder to tilt properly and will become slippery unless they are textured, because the grout lines are separate from each other. Textured or not, smaller tiles offer more traction and are typically the norm for shower floors. The options are almost limitless.
Shower or bathtub
Given the option of a bathtub or just a shower, ask yourself how many baths you take a year. To my clients, it's not that they're renovating their home for a future buyer, it's that they're renovating it for themselves
I have to remind you. Even if you can only live in your home for another five years, it's worth doing it yourself. Also, there is no guaranteed way to tell a future buyer what will be attractive.
Do you have a place to put the medicine cabinet? Often this is a great way to save a few inches of space on a shallow paper, and additional framing usually doesn't break the budget. If that's not an option, make sure your toilet seat has enough space for your medicine cabinet to come out 4 to 5 inches.
Think of setting up a toilet with drawers, not doors. Drawers are easier to access and organize. They can be cut around the plumbing and be extra large to accommodate large items.